1. Field of the Invention
The present invention relates to the field of carbon nanotubes and to the field of molecular sized electromechanical devices which contain nanoscale levers, such as carbon nanotubes and the like.
2. Related Art
The industrial revolution was driven by the development of efficient linear-motor-based steam engines capable of operating machinery and relieving human and animal physical labor. Even today, many mechanical systems are powered by linear motors (such as the internal combustion engine and hydraulic and pneumatic rams), using gas or liquid working fluids in piston/cylinder/control valve arrangements not unlike those of the original steam engines. Recent progress in the extreme miniaturization of electronic (Refs. 1, 2) and mechanical (Ref. 3) systems raises the question: can similar linear motors be fabricated and operated at the molecular or nanoscale?
The direct scaling of many proven macroscopic motor designs to nanometer length scales appears challenging. Vapor phase engines, for instance, become sensitive to single-particle effects—at room temperature one molecule in a piston volume of 10 nm3 already exerts a pressure of more than 4 atmospheres. Molecular-scale linear motors (Refs. 4, 5), such as kinesin (Ref. 6), myosin (Ref. 7), and dynein (Ref. 8), already exist in nature. However, such structurally complex biomotors have limited force capability and require tightly controlled chemical environments for operation (Ref 9), features which restrict their applications potential and make them questionable models for synthetic analogues.
Thus there is a need for an efficient nanoscale size motor that can be assembled efficiently and driven by electrical, magnetic, optical or similar energy which can operate on single or small clusters of atoms.
Den et al. U.S. Pat. No. 6,628,053 discloses a carbon nanotube device comprising a support having a conductive surface and a carbon nanotube, wherein one terminus of the nanotube binds to the conductive surface so that conduction between the surface and the carbon nanotube is maintained. The device is used as an electron generator.
Falvo et al. Nature 397:236-238 (Jan. 21, 1997) disclose studies involving the rolling of carbon nanotubes using atomic force microscope (AFM) manipulation of multiwall carbon nanotubes (MWCNT, termed in the paper “CNT”).
Minett et al. Current Applied Physics 2:61-64 (2002) disclose the use of carbon nanotubes as actuators in which the driving force is obtained from a deformation of the nanotube when a charge is applied. The authors, in their review also disclose the growth of nanotubes across two metal contacts in a process that involved E-beam lithography and selective patterning.
Fraysse at al. Carbon 40:1735-1739 (2002) discloses carbon nanotubes that act like actuators. In concept, a SWNT may be disposed above a substrate and between a pair of metal-on-oxide layers. The nanotubes act as actuators though a cantilever effect achieved through longitudinal deformation of the nanotube.